Method for producing tablets for sound-records.



T. A. EDISON.

METHOD FOR PRODUCING TABLETS FOR SOUND-RECORDS.

APPLICATION FILED DEC. 20, 19M.

Llfifil 3e, Patented July 13, 1915.

THOMAS A. EDISON, OF LLEWELLYN BARK, WEST ORANGE, NEW JERSEY, ASSIGNORTO NEW JERSEY PATENT COMPANY, OF WEST ORANGE, NEW JERSEY, A CORPORA-TION OF NEW JERSEY.

Specification of Letters Iatent.

Patented July 13, 1915 Application filed December 20, 1911. Serial No.686,888.

To all whom it mag concern:

Be it known that I, THOMAS A. EDIsoN, a citizen of the United States,and a resident of Llewellyn Park, West Orange, in the county of Essexand State of New Jersey, have invented certain new and usefulImprovements in Method for Producing Tablets for Sound-Records, of whichthe following is a description.

My invention relates to methods and appara-tus for producing tablets forsound records, more particularly for sound records of the flat or disktype having a surface of an exceedingly hard material such, for example,as the condensation products, which form the subject matter of the U. S.Patents of Jonas W. Aylsworth, Nos. 1,102,630, 1,020,593, 1,098,608 and1,040,137, the method only being claimed in this case. In pressing ablank tablet of this type into the record matrix, unless the tablet orthe base or backing therefor is of substantially uniform densitythroughout, it is practically impossible on account of the excessivepressure in the hard spots and the deficlency of pressure in the softspots to obtain a perfect impression over the entire record surface.Furthermore, I have found in practice that if an ordinary mass ofpowdered material or stock of substantially uniform thickness is placedin a mold between the ordinary rigid mold plates, it is practicallyimpossible to obtain the necessary evenness or uniformity in the densityof the tablet, the unevenness being apparently due to the fact that thepowdered material lies more compactly in some places than in others.

The principal object of my invention is to provide an improved processand apparatus whereby a tablet having the. necessary uniformity ofdensity may be readily obtained from powdered material or stock.

Other objects of my invention will appear more fully in the followingspecification and appended claims.

In conformity with my invention, the material or stock from which thetablet is molded is placed in a powdered condition in the mold and isthere subjected to a uniform pressure applied insuch a way as to compactthe stock to a mass of substantially uniform density. After this, thesurface of the stock is evened off in any suitable way recordimpression.

way so long as it acts uniformly over thewhole of the exposed surface ofthe stock in the mold, I prefer to apply the same by a fluid, such asair, .under pressure; as such a pressure acts readily upon all portionsof the surface of the stock, regardless of the irregularities therein.In order to prevent scattering of the powdered material by the air orother fluid employed, I preferably apply the fiuid pressure to the backof a flexible membrane or diaphragm of suitable material, such asrubber, adapted to engage the surface of the stock.

After the stock is compacted, as described above, to amass of uniformdensity, the

surface thereof to which the pressure has been applied is found to beundulatory or covered with high and low spots. To even off this surfaceI preferably again fill the mold, after which the stock may be moldedunder heat and pressure to the desired shape. The surface of the tabletis now provided with a veneer or veneers of impressible material adaptedto receive the Although this veneer may be applied in any suitable way,I pre fer to apply the same by the process set forth in an applicationof Jonas W. Aylsworth, Serial No. 579,130, filed August 26, 1910, andentitled Method of molding sound records and other objects. Inaccordance with this process, the veneer is formed by coating thematerial of which the same is composed upon the surface of a blank mold,the tablet to be coated being pressed into contact with the coating inthe mold with the application of suflicient heat to cause the coating tofirmly adhere to the tablet. After this, the coated tablet may beremoved from the mold and pressed with sufiicient application of heatinto a suitable record mold to cause the sound record to be formed onthe surface thereof. In order to cause the surface veneer to adherefirmly to the rough backing, I preferably cover the latter, prior to thetransfer of the Veneer, with a very thin coating of the material ofwhich the veneer is formed. This coating should be pressed into therough tablet in order to completely fill the surface pores thereof.

In order that my inve ion may be more fully understood, attention ishereby directed to the accompanying drawing forming a part of this secification and illustrating various steps 0 my improved process and theap aratus for carrying the same into effect.

11 the drawings, Figures 1 and 2 represent central vertical sectionalviews of the lower mold member filled with stock and covered with oneform of my improved apparatus for compacting the stock, the dotted linesin these two figures indicating the respective positions of the flexiblediaphragm or membrane after successive compactings. Fig. 3 represents asimilar view of the complete mold after the formation of the rou htablet. Fig. 4 illustrates the rough tab et covered with a thin coatingof the surface material prior to the application of surface veneers tothe opposite faces thereof. Fig. 5 represents a similar view of thecoated tablet placed in a mold for compressing the coating into thetablet and for forming the peri hery of the latter. Fig. 6 represents asimilar view of the apparatus for securing the surface veneers to thetablet, the tablet and the veneers being shown in position in theapparatus.

As shown in the drawings, the numeral 1 indicates the base of a moldhaving a centering pin 2, and a recess 3 of uniform depth in which thestock or material 4 to be molded is placed. A member 5 provided with arecess 6 is adapted to rest on the base of the mold with the recess 6above the recess 3, the former recess being covered by a flexiblemembrane or diaphragm 7, forming thereby a closed chamber in the member5. The numeral 8 designates a suitable air or fluid inlet for the saidchamber. The membrane 7 is preferably provided with an upwardly directedportion 9 engaging firmly in a pcripheral recess 10 in the member 5whereby the membrane or diaphragm 7 is firmly secured to the member 5.If the said membrane is made of a yieldable material such as rubber, thecontraction of the same when stretched over the member 5 will besuflicient to draw the flange 9 into close contact with the recess 10.The membrane 7 extends preferably across the portion of the member 5adapted to engage the base of the mold so that when the said member isheld in position on the said base by a suitable pressure applying member11, the membrane because of its yielding character will form a tightjoint between the base of the mold and the member 5.

In carrying out my improved process, the base of the mold is pre erablyfilled with powdered stock, after which the compacting device abovedescribed is placed above the same and held firmly thereon by the member11, fluid under pressure being thereupon in troduced from any suitablesource through the inlet 8 into the chamber above the membrane 7 whichis thereby pressed upon the record material or stock to compact the samein the mold. By reason of the uniformity of the pressure u on the uppersurface of the membrane an the ability of the latter to conform to theexact shape of the upper surface of the stock, the latter is compactedto a mass having a substantially uniform density throughout, theposition of the membrane after this operation being shown in dottedlines in Fig. 1. The member 5 and the parts connected thereto are nowremoved from the top of the mold and the latter is again filled andleveled off with powdered stock to even off the surface of the latter.This operation of compacting the stock and evening off the upper surfacethereof may be repeated any desired number of times, but, as abovestated, I have found in practice that satisfactory results are obtainedwhen the stock is compacted and evened off a single time. In Fig. 2, thedotted lines indicate roughly the position of the diaphragm or membraneafter a second compacting operation. After the material has beensuitablv compacted, the upper member 12 of the mold is forced downwardlyupon the stock, suflicient heat being applied to cause the latter tobecome slightly plastic; so that after cooling, a. rough I' klnt fbstantially uniform density and thickness is obtained.

The composition for the rough tablet may be mixtures of wood pulp orother filling agents and a fusible condensation product such as thewellknown shellac substitutes and other substances, which are referredto by the term phenol resin in applications of Jonas W. Aylsworth,Serial Nos. 496,060

- and 541,764, the term phenol resin being intended to include cresoland other equivalents of phenol. A suitable composition may be formedfrom the ordinary shellac mixtures with wood pulp. Any other suitablecomposition may be employed. The rough blank or tablet having beenobtained, the same is provided with a thin coating of the material whichis to constitute the impressible surface of the tablet, this coatingbeing shown at 13 in Fig. 4. This material may be and preferably is theenamel lacquer or varnish described in application of Jonas W.Aylsworth, Serial No. 543,239,. which lacquer or varnish comprisesbroadly-a fusible resin of phenolic origin, which has mixed therewith asubstance which is adapted to react with the resin upon the applicationof sufiicient heat to form a hard insoluble condensation product, thelacquer or varnish also containing a plasticity ingredient whereby it isadapted after hardening to receive a sound record impression uponapplication of suflicient heat. This varnish 1 "13 is preferablylsprayedonto the rough tabpress the latter between the two plates 14 and 15 of amold, sufficient heat being applied to permit the ready forming of theperiphery ofthe tablet, asindicated in Fig. 5, but notto harden the'varnish. Blank molds 16 and 17 are now coated, preferably in the samemanner as the rough blank, with a solution of thesurface material. Thesemolds havingbeen coated, the same are dried; and the rough tablet isthen pressed between the same in contact with the surfacing layers orveneers formed upon the same, asfclearly indicated in Fig. 6. In thesaidfigure, thernumeral 18 represents the "lower 'memberof a press. Itis understood that during the operation sufiicient heat is applied tocausefthe welding of the surface veneers to the blank and the transferof the said veneersto the rough blank or tablet upon the :cooling andwithdrawal of the same from the mold. If the enamel lacquer or varnishreferred to above is employed for the surfacing materiahthe same may beconverted on the application of heat into a final infusible insolublerefractory product. The heat to cause this transformation may be appliedbefore the veneers are transferred to the rough tablet or blank, or thesame may be applied during the said operation. I, however, consider theformer method preferable because the residues of the solvent employed inmaking the varnish are thereby permitted to escape more readily. Theheating is preferably done in successive stages beginning at about 120F. and ending at 220 F. or higher according to the nature of theparticular enamel used. When the record blank is made in the mannerdescribed above, I have found that an accurate sound record may beimpressed therein regard%ess of the hardness of the surface materiaWhile I have illustrated the application of surface coatings to both ofthe faces of the tablet, it is evident that if desired only one face ofthe tablet need be coated. Numerous other modifications may be made inthe process and also the apparatus above described without departingfrom the spirit of my invention, the latter being limited only asdefined by the terms of the appended claims.

What I claim as new and desire to protect by Letters Patent of theUnited States is as follows:

1. The process of making tablets for sound records, which comprisesplacing in a mold a quantity of finely divided stock, pressing the sameto a compact mass having a substantially uniform density throughout,evening off the surface of the compacted mass, and compressing the samewith the application of heat to form a tablet of desired shape,substantially as described.

2. The process of making tablets for sound records, which comprisesplacing in a mold a quantity of finely divided stock, forming the sameinto a compacted mass having a substantially uniform density throughout,evening off the surface of the compacted mass to form a mass of stock ofuniform thickness, and compressing the same with the application of heatto form a tablet of desired shape, substantially as described.

3. The process of making tablets for sound records, which comprisesplacing in a mold a quantity of powdered stock, compressing the same toa compact mass having a substantially uniform density throughout,evening off the surface of the compacted mass with additional powderedstock, and compressing the same with the application of heat to form atablet of desired shape,

substantially as set forth.

4. The process of making tablets for sound records, which comprisesplacing into a mold a quantity of powdered stock, compact-ing andforming the same into a mass havlng an even upper surface and asubstantially uniform density throughout, com pressing the same with theapplication of heat to form a tablet of desired shape, and applying tosaidtablet a veneer of hard impressible record material, substantiallyas set forth.

5. The process of making record tablets which comprises placing into amold a quantity of powdered material which is plastic when hot and hardwhen cold, compacting and forming the same into a mass having acomparatively even upper surface and a substantially uniform densitythroughout, compressing the same with the application of heat to form atablet of desired shape, and applying to said tablet a veneer ofmaterial which becomes slightly softened but not sufficiently plastic toflow when hot, substantially as set forth.

6. The process of making tablets for sound records, which comprisesplacing in a mold a quantity of powdered stock, compressing the same bymeans of fluid pressure to a compact mass, evening off the surface ofthe compacted mass, and compressing the same with the application ofheat to form a tablet of desired shape, substantially as set forth.

7. The process of making tablets for sound records, which comprisesplacing in a mold a quantity of powdered stock, applying a flexiblecovering to the top of said stock, compressing the latter to a compactmass by the application of fluid pressure to the said covering, eveningofit the surface of the compacted mass, and compressing the same withthe application of heat to form a tablet of desired shape, substantiallyas set forth. a

8. The process of making tablets for sound records, which comprisesplacing in a mold a quantity of powdered stock, applying a flexiblecovering to the top of said stock, compressing the latter to a compactmass by the application of fluid pressure to the said covering, eveningoff the surface of the compacted mass, compressing the same with theapplication of heat to form a tablet of desired shape, and applying tosaid tablet a veneer of hard impressible record material, substantiallyas set forth.

9. The process of making tablets for sound records or the like, whichcomprises placing in a mold a quantity of powdered stock, applying ayielding covering to the top of said stock, compressing the atter to acompact mass by the application of pressure to said covering, eveningoff the surface of the compacted mass, and compressing the same with theapplication of heat to form a tablet of desired shape, substantially asset forth.

10. The process of making tablets for sound records or the like whichcomprises v placing in a mold a quantit of finely divide stockcomprising a ler and a binder therefor, compacting the same to a. masshaving substantially uniform density throughout, evening off the surfaceof thecompacted mass, and compressing the same with'the application ofheat to form a tablet of desired shape, substantially as set forth.

11. The process of making tablets for sound records or the like whichcomprises placing in a mold a quantity of finely divided stockcomprising a ler and a phenolic binder therefor, compactin the same to amass having substantially umform density throughout, evening off thesurface of the compacted mass, and compressin the same with theapplication of heat to orm a tablet of desired shape, substantially asset forth.

12. The process of making tablets for sound records or the like whichcomprises placing in a mold a quantit of finely divided stock comprisinga ller and a binder therefor, compacting the same to a mass havingsubstantially uniform density throughout, evening 011 the surface of thecompacted mass, compressing the same with the application of heat toform a tablet of desired shape, and applying a surface veneer to saidtablet, substantially as set forth.

This specification signed and witnessed this 19th day of December 1911.

THOS. A. EDISON.

Witnesses: FREDERICK BACHMANN, ANNA R. KLEHM.

